Recently the use of stereo 3D to view games and videos has become increasingly popular. Stereo 3D devices such as 3D projectors, 3D TVs and so on are widely used for watching movies, stereo 3D TV programs and other stereo 3D videos. However, users do not have the same experience when watching the same stereo 3D video on different devices when screen size varies between devices. For example, the user experience is different when a user watches a stereo 3D video designed for a 64 inch screen on a 32 inch screen instead of the designed-for 64 inch screen. Assuming that the expected viewing distance for 64 inch screen is 4 meters and the expected viewing distance for 32 inch screen is 2 meters, in present day design the presentation of stereo 3D videos is such that the perceived depth range for a 32 inch screen is much smaller than that for 64 inch screen. For example, although a 32 inch screen is exactly half the dimension of a 64 inch screen, when a stereo 3D video designed for the 64 inch screen is displayed on the 32 inch screen the perceived depth range may be much less than half of the perceived depth range experienced when watching the stereo 3D on a 64 inch screen. For example, the perceived depth range on the 32 inch screen may be less than ¼ that of the perceived depth range on a 64 inch screen.
This large degradation in the ability to present depth in a stereo 3D video when screen size of a viewing device is smaller than that of the designed device limits the quality of experience for many users since stereo 3D videos may be deployed on multiple different device types. Moreover, this may limit the growth of stereo 3D video because of the need to custom design the stereo 3D video for different device screen sizes.